Let f be a dominant meromorphic self-map of large topological degree on a compact Kähler manifold. We give a new construction of the equilibrium measure µ of f and prove that µ is exponentially mixing. As a consequence, we get the central limit theorem in particular for Hölder-continuous observables, but also for noncontinuous observables.
DECAY OF CORRELATIONS
755THEOREM 1.1 The measure µ is exponentially mixing in the following sense: for every > 0 and 0 < α ≤ 1, there exists a constant A ,α > 0 such thatfor all n ≥ 0, for every function ψ ∈ L ∞ (µ), and for every Hölder-continuous function ϕ of order α. If a real-valued Hölder-continuous function ϕ is not a coboundary and verifies µ, ϕ = 0, then it satisfies the CLT theorem.We recall in Section 2 the Gordin-Liverani theorem and in Section 3 some properties of the Sobolev space W 1,2 . The space of test functions W 1,2 * and a subspace W 1,2 * * are introduced in Section 4. This is the key point of the method. The new space W 1,2 * seems to be useful for complex dynamics in several variables. In complex dimension 1 it coincides with the space W 1,2 . In higher dimensions it takes into account the fact that not all currents of bidegree (1, 1) are closed. It enjoys the composition properties under meromorphic maps, useful for a space of observables. In Section 5, we give the new construction of µ, and in Section 6 its statistical properties. Note that the geometric decay of correlations for Hénon maps was recently proved in [6] using the dd c -method. Like the dd c -method, the d-method can be applied to some meromorphic correspondences and to random iteration [7].Notation. We will use different subspaces of L 1 (X ). Most of them carry a canonical (quasi) norm. For the space C 0 (X ) of continuous functions we use the supnorm, for the space Lip(X ) of Lipschitz functions the norm · L 1 + · Lip where ϕ Lip := sup x =y |ϕ(x) − ϕ(y)| dist(x, y) −1 , and for the Hölder space C α (X ) the norm ϕ C α := ϕ L 1 + sup x =y |ϕ(x) − ϕ(y)| dist(x, y) −α . We use the (quasi)norm · E + · F for the intersection E ∩ F of E and F and write L p instead of L p (X ) when there is no confusion. The L p norm of a form is the sum of L p norms of its coefficients for a fixed atlas of X . The topology that we consider is a weak topology. That is, ϕ n → ϕ in E if ϕ n → ϕ in the sense of distributions and ( ϕ n E ) is bounded. The continuity of linear operators : E → F is with respect to these topologies of E and F. The inclusion map E ⊂ L 1 (X ) is always bounded for the associated (quasi)-norms and is continuous in our sense.